Systems which include means for converting analog signals to digital form, then compression filtering and Huffman encoding the signals for recording or for transmission to a remove location, together with playback or receiver means which include a Huffman decoder, a digital reconstruction filter and means for converting the decoded and filtered digital signals back to analog form are shown in the above-identified U.S. Pat. No. 4,449,536, and in an article by U. E. Ruttimann and H. V. Pipberger entitled, "Compression of the ECG by Prediction or Interpolation and Entropy Encoding", IEE Transactions on Biomedical Engineering, Vol. BME-26, No. 11, pp. 613-623, November, 1979. A similar system is shown in an article by K. L. Ripley and J. R. Cox, Jr. entitled, "A Computer System for Capturing Transient Electrocardiographic Data", Pro. Comput. Cardiol. pp. 439-445, 1976. The above teachings employ a digital compression filter consisting of one or two zeros at dc frequency as a means of reducing the variance, or energy, of the signal prior to the Huffman encoding. As will become apparent, minimizing the variance of the signal prior to encoding does not, in general, reduce the bit rate needed for accurate transmission of the encoded waveform representation, and that only certain filter constructs achieve this objective, known more properly as minimizing the entropy of the signal.